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ENZYMES By chynnel…read more

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Enzymes are biological catalysts. Yes, they speed up metabolic reactions
and provide an alternative route for a reaction to take place.
Enzymes can either be intracellular or extracellular.
Enzymes are proteins (globular) and there shape is determined by the
interactions between parts of the molecule which gives it its final 3D shape.
Enzymes are similar because:
There are all catalysts
They are soluble in water and they are globular
They are specific
They are affected by pH, temperature, substrate and enzyme concentration…read more

Slide 3

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oThey are used in the formation and breakage of bonds in biological bonds.
They require at least one specific enzyme to catalyse the reaction.
oThey are also used to speed up process such as digestion, respiration and
photosynthesis.…read more

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oEnzymes are useful as they reduce the amount of energy needed for the
reaction to proceed. This is known as the activation energy.
oThe enzyme provides an alternative route which allows the reaction to take
place at lower temperatures quickly.
oTwo types of mechanisms used to explain how mechanisms work are the
induced fit hypothesis and the lock and key mechanism.…read more

Slide 5

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oThe lock and key mechanism states that the enzyme has high specifity
because the active site is specific to a particular substrate.
oThe substrate has a complementary shape to the active site and this means
it can bind to the active site and this fits so it can be held in place and the
reaction takes place to form an enzyme-substrate complex which after will
release the product.
oThis is why it is given the term as the substrate is the `key' and this fits into
the active site `lock'.…read more

Slide 6

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oThe induced fit hypothesis simply explains that when the substrate collides
into the enzyme's active site it binds and the enzyme molecule slightly
changes shape so the substrate fits in place and the enzyme can fit closely
around it.
oThe substrate is held by the opposite charged groups on the substrate and
active site.
oThis then allows the reaction to take place forming an enzyme-substrate
oThis puts strain on the substrate allowing the reaction to take place more
oThis produces a product (enzyme-product complex) and as the products are
a different shape substrate and to the enzyme's active site, it no longer fits…read more

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